LM3551/2

SW

FB

FET-T

FET-F

D1

L1

SS

OVP

FTO

SD/

EN

T/F

LUMILED

LXCL-PWF1

Flash LED

Sharp

GM5BW05340A

Flash LED

LM3551/2

SW

FB

FET-T

FET-F

D1

L1

SS

OVP

FTO

SD/

EN

T/F

GND

LM3551, LM3552

www.ti.com

SNVS371C – AUGUST 2005 – REVISED MARCH 2011

LM3551 /LM3552 1A White LED Driver with Flash Timeout Protection

Check for Samples: LM3551, LM3552

1

FEATURES

APPLICATIONS

2

•

Up to 1A Total Drive Current

•

White LED Camera Flash

•

Flash Timeout Protection

•

White LED Torch (Flashlight)

•

Independent Torch/Flash/Shutdown Modes

•

DSC (Digital Still Camera) Flash

•

LED Disconnect in Shutdown

•

Cellular Camera Phone Flash

•

Programmable Soft-Start Limits Inrush Current

•

PDA Camera Flash

•

Over-Voltage Protection

•

Camcorder Torch (Flashlight) Lamp

•

Wide Voltage Range 2.7 to 5.5V

•

1.25MHz Constant Switching Frequency

•

Small, Low Profile Package, Non-Pullback

WSON(4mm x 4mm)

DESCRIPTION

The LM3551 and LM3552 are fixed frequency, current mode step-up DC/DC converters with two integrated

NFETs that can be used for precision LED brightness control. The devices are capable of driving loads up to 1A

from a single-cell Li-Ion battery.

The LM3551 and LM3552 can drive one or more high current flash LEDs either in a high power Flash mode or a

lower power Torch mode using the TORCH/FLASH pin. A programmable Timeout function on the FTO pin forces

the internal NFETs to turn off after a certain user defined time. An external SD pin (LM3551) or EN pin (LM3552)

is available to put the device into low power shutdown mode. During shutdown, the feedback resistors and the

load are disconnected from the input to avoid leakage current paths to ground.

User programmable soft-start circuitry has been integrated to eliminate large inrush currents at start-up. Over-

voltage protection circuitry and a 1.25MHz switching frequency allow for the use of small, low-cost output

capacitors with lower voltage ratings. The LM3551 and LM3552 are available in a low profile 14-pin WSON

package.

Typical Application Circuits

1

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2

All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Copyright © 2005–2011, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.